All things related to multicast

[Bharat Joshi <>]

Hi Stig,

    Thanks for responding to this query. Please see in line.

> >>> * Do existing IGMPv3 capable applications support Exclude mode for ASM
> >>> groups?
> >> I don't think so.
> >
> > Ok. So most of the times, applications will use one or multiple source 
> > addresses for ASM groups in INCLUDE mode.
> >
> >>> * Also do anyone see a need for EXCUDE mode to be supported for their
> >>> existing applications or any new applications they will create or like
> >>> to use?
> >> I don't think there is necessity to use EXCLUDE mode for general
> >> multicast applications, except some service discovery protocols, which
> >> usually use (*,G). In other words, no use with source specific EXCLUDE
> >> mode join/leave.
> >
> > So EXCLUDE mode is typically used to allow all and never with a source 
> > list.
> 
> While I don't know any applications, it might be useful for say
> conferencing to exclude sources for muted participants.

Ok.

I am looking for such cases where it may be useful and till now I could
not find any application using it.

The biggest issue I see is that if someone uses EXCLUDE mode, though he
might be able to avoid traffic from some specific individual but with
this he might start getting unwanted traffic from all others which he
did not even know existed.

Regards,
Bharat

> Stig
> 
> >>>      I just wanted to know on how much this complex functionality
> >>> ['Exclude Mode support'] being used in the field?
> >> I cannot imagine it'll be needed.
> >>
> >> In fact, eliminating EXCLUDE (S,G) join/leave is "beneficial" for
> >> multicast communications. For example, it reduces host/router/switch
> >> implementation costs and routing tree maintenance costs. It's not just
> >> "unneeded". This is my thought.
> >
> > Ok. I am also of the same opinion.
> >
> > So with above assumptions, it looks like an IGMPv3 host/router part 
> > implementation or IGMPv3 snooping which does not handle EXCLUDE with 
> > source list should be able to work in multicast networks.
> >
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